Gas Guzzling, Giant RV's

[Mark_K5LXP]

Came across this article for EV driving RV'ers.

https://www.curbed.com/2018/8/29/177...tric-dethleffs


Mark B.
Albuquerque, NM

[TonyMac]

It's bound to be successful because electricity is free and comes out of the receptacle.

[Winterbagoal]

If James Dyson, and 200 engineers, trying for 2 years to make a commercially viable EV car, finally gave up, it can't be done.

[Kluffinator]

Actually, after reading this article it makes a lot of sense. As one who used to tow a travel trailer, the idea that the trailer itself could provide some motive power, especially in going up hills, is very appealing. I well remember to days of going up some North Georgia inclines and barely making 35 MPH, even with a big V-8. To have the trailer self lighten it's load on the engine and transmission of the truck would be a welcomed innovation.

In addition I know from own experience with regenerative braking on a Prius just how much the brakes are preserved.

The cost of gas and loss of MPG is always a subject that comes up with non-RV'rs and may be real impediment for others to enter our ranks. This technology shows promise in helping to make the the enjoyment of RVing more affordable for others in terms of fuel consumption and pulling a trailer with a smaller power-train.

The other aspect mentioned in the article was the concept of being able to self park the trailer without being coupled to the truck. Imagine the campsites that would suddenly be accessible that are other wise too awkward to navigate with a larger set-up.

And finally, this concept should be attractive to those in California who are dealing with electrical blackouts (as if they lived in a third world country) since the trailer would be an onsite power supply for their home.

I see a lot of positives with this innovation. Advances in technology continues to make our experience with RV's more enjoyable so I fail to understand the nay-saying on this on.

[jcussen]

Originally Posted by Kluffinator

Actually, after reading this article it makes a lot of sense. As one who used to tow a travel trailer, the idea that the trailer itself could provide some motive power, especially in going up hills, is very appealing. I well remember to days of going up some North Georgia inclines and barely making 35 MPH, even with a big V-8. To have the trailer self lighten it's load on the engine and transmission of the truck would be a welcomed innovation.

In addition I know from own experience with regenerative braking on a Prius just how much the brakes are preserved.

The cost of gas and loss of MPG is always a subject that comes up with non-RV'rs and may be real impediment for others to enter our ranks. This technology shows promise in helping to make the the enjoyment of RVing more affordable for others in terms of fuel consumption and pulling a trailer with a smaller power-train.

The other aspect mentioned in the article was the concept of being able to self park the trailer without being coupled to the truck. Imagine the campsites that would suddenly be accessible that are other wise too awkward to navigate with a larger set-up.

And finally, this concept should be attractive to those in California who are dealing with electrical blackouts (as if they lived in a third world country) since the trailer would be an onsite power supply for their home.

I see a lot of positives with this innovation. Advances in technology continues to make our experience with RV's more enjoyable so I fail to understand the nay-saying on this on.

Agree, probably not for the die hard full timer, or for the 500 mile a day guy, but for the weekender going a couple of hundred miles to his local state park, a great idea. And I also like the fact you have a cool or warm place to sleep when you lose the grid, and not have to rely on generators and finding fuel for them, at least for a while.

[Kluffinator]

I wonder how much weight the panels batteries and drive axles add to the trailer. If significant the boost when needed might be offset by the extra fuel required to pull in tow only mode. Either way having that extra boost and the other advantages mentioned would still be a favorable outcome.

[Kluffinator]

If this proves out the same technology could be applied to the trucking industry. I’m assuming.

[TonyMac]

So you get there and the trailer batteries are dead from driving the battery-laden trailer all day. Nice...

[Gordon Dewald]

This sounds like a great idea.

People towing 4 down could have the spouse sit in the toad and use the toad engine to help increase the mileage of the motorhome.

[Trapper2022]

I’m sure some form of electric is in our kids future but long way from ours. Nowhere do you find/see interior layout or what it costs. Article’s Say testing of concept in 2019. I could not find any follow up results. If some here has links please share. May work in Europe where countries are close together but not sure about this country. I live in Houston and it is 3 to 10 hours to the borders of the state. Can’t wait to see real world class c solutions. Right now when I go to gulf shores I drive 8 to 10 hours in one day to get there. The electric equivalent is a ways off.

Enjoy the journey

[Kluffinator]

Originally Posted by Gordon Dewald

This sounds like a great idea.

People towing 4 down could have the spouse sit in the toad and use the toad engine to help increase the mileage of the motorhome.

Well, now that you mention it. Lets think about how this could work. Lets say that your toad is E/V or hybrid. (not likely because most use a CV transmission which don't work well for towing. But for the sake of discussion assume that issue is worked out)
Consider that the drive-train on the toad is controlled by a processor coupled with load sensors on the hitch and to the MH drivetrain computer.
During times of increased loading from ascending hills, merging or passing the toad drivetrain engages, matches the input speed of the MH and reduces the loading to 10% or so of unassisted. (you need to maintain some loading in order to provide towing stability).

The EV toad batteries could be maintained through regenenrative braking and also when descending hills, which would have the added benefit of reducing the braking load on the MH. And possibly by taking some power from the generator.

So instead of focusing on the potential of increased MPG, which may or may be possible, think instead of the potential for improved drive-ability. I know my own MH drives much more responsively without the Toad than with it.

As the technology improves for autonomous driving, a self driving toad coupled to the MH could do exactly what you suggest. While the math may or may not work out to improve the combined MPG, I believe that there is a potential for improvement to the performance. And I believe this technology is closer to the doorstep than we may know.

But lets also consider the math. Assume a 22K Lb MH getting 7 MPG without Toad. Add a 4K Lb Hybrid toad getting 45 mpg. Combined weight of unassisted toad and MH of 26K lb getting 6 mpg. Using a Hybrid toad assisting the MH could result in a improvement of 25% in fuel required to move the mass vs an unassisted toad.

In other words the hybrid toad would not improve the overall MPG of the MH by itself but could very well improve the MPG of the MH pulling a toad.

IMHO of course.

[Mark_K5LXP]

Originally Posted by Kluffinator

Consider that the drive-train on the toad is controlled by a processor coupled with load sensors on the hitch and to the MH drivetrain computer.

I'm considering the DOT qualification process for that system.

The EV toad batteries could be maintained through regenenrative braking and also when descending hills,

[EV hat on]
Regenerative braking actually returns little energy to the traction pack. Typically about 5% in normal driving. In the toad scenario you could potentially return more because you have the added mass of the MH but unless the regen is made to handle that amount of energy (and why would it be, it was only designed for a 4Klb car) then you're not getting much out of it.

the hybrid toad would not improve the overall MPG of the MH by itself but could very well improve the MPG of the MH pulling a toad.

Nothing is free. At the end of the day you're moving x000's of pounds down the road with the same rolling resistance and coefficient of drag. There are a number of imponderables like ICE efficiencies at various loads but my guess is what gas you save running the MH gets put into the toad, plus wear and tear on a 2nd vehicle. The only benefit to the idea is reducing the towing load on the MH but managing a separate powerplant and driveline doesn't seem trivial to me.

The pusher idea isn't new though. You can get them for bicycles and a few conversion EV enthusiasts have made them out of a front clip of a front wheel drive car. They basically manage it by remoting the pusher throttle control and using the pusher as the primary motive force.

Mark B.
Albuquerque, NM

[jcussen]

Regenerative braking can be actually fairly efficient and can return 60 to 70% to the battery. Have heard stories of EV's batteries going from 50 to 70% after a long downhill run, breaking using regen only.

https://electrek.co/2018/04/24/regen...-how-it-works/

[Mark_K5LXP]

Originally Posted by jcussen

Regenerative braking can be actually fairly efficient and can return 60 to 70% to the battery.

The regeneration efficiency (kinetic to chemical), and amount of usable power returned to the pack are two separate things. Most of the energy of a pack's charge will be expended moving the vehicle. Only a very small percentage of the time driving a vehicle is spent shedding energy by braking, or in this case, returning some of that energy to the pack. Even in a gas car, think about how much time your foot is spent on the gas pedal, and how much time on the brake. Not directly equivalent I know, but a basic example of the point. More brake time gives you more regeneration but you don't end up going very far just using the brakes. You have to put energy into the car for any opportunity to get it back out. That energy comes from the pack and when you factor all the losses (drag, friction, conversion) braking isn't usually a large part of total energy used to begin with, so it doesn't have a lot of potential energy to return.

Have heard stories of EV's batteries going from 50 to 70% after a long downhill run, breaking using regen only.

But you have to get up that hill to be able to coast down it. So even if you somehow returned 20% of the charge to the pack, you paid with probably 2 or 3 times that much to get it up that hill, or back up that hill on the return trip . Not saying that regenerative braking doesn't work or isn't useful, but it doesn't give as big a boost to overall range in typical driving as one might think.

Mark B.
Albuquerque, NM